RE: [EnergyPlus_Support] Problem with pumps

All you need to match are the plant node names and zone connection names in the splitter/mixer branches.

You can detach the non-zone DHW storage tank from the boiler and make it another plant loop with a separate heat source, which can be solar collector, gas, or electric, or mixed.

There is a list of objects which can have autosize values in the I/O ref. manual. The examples may have autosize already in place. Instead of fixing all branch flow rates, etc. according to the eQUEST values, use only the maximum limiting values and allow EPlus to autosize the working values and then compare with your real system.

If the limits are set correctly, you may not need to remove the autosized fields, it they are close to your system values.

Since your DHW is fed from the boiler. the DHW temperature may be affected by the zone demand. The provision of a bypass branch allows the boiler to maintain the set point temperature when there is no demand. May be you should try adding this branch which was shown in my first diagram.

Dear Dr. Li,

Following your advices, I've finally came to a right solution. I've attached the diagram and the .idf file. I have used schedules and some input data from various example files, so the numbers might seem unreal. I used them just for a quick test until I find the right path.

Best regards,

Lyuben

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: Linda Lawrie <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Wed, February 16, 2011 11:42:38 PM
Subject: RE: [EnergyPlus_Support] Problem with pumps

Are you trying to modify the IDF for SOFIA_BGR Design_Conditions, which was posted in the group around 25 January under Ref. below?

Date: Tue, 25 Jan 2011 03:34:45 -0800
Subject: [EnergyPlus_Support] Simple Heating System

What have you changed in your IDF? Please attach or post as a file and not as text in the mail.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: lbarosow@xxxxxxxxx
Date: Tue, 15 Feb 2011 12:33:08 -0800
Subject: Re: [EnergyPlus_Support] Problem with pumps

Dear Dr. Li,

Thank you for the suggested solution. I found the diagram but I think that it is for different system than the one I have and if I use it then the components won't be sized correctly.

I've prepared and attached a new scheme, which I think gives a better illustration of the system that I need to model. Basically there is a diesel boiler that supplies all the heat for heating and domestic water use for two zones. The I/O temperatures of the heating system will be 80/60 oC. The tempearture of the DHW will be 65 oC and will be achieved through indirect heating in a water heater (for each zone), using the water from the boiler (80 oC). My original idea was to model each branch after the splitter as a separate demand, but the main problem occured that there are pumps after the splitter. And EnergyPlus says they can't be there. Moreover, the water heaters also must be on the supply side and probably this would generate another error message. I understand that I have to somehow model all the splitter outlet branches including the pumps and water heaters as supply ones but for now I can't find a way to do that. Any help would be highly appreciated!

Best regards!

Lyuben

From: YuanLu Li <yli006@xxxxxxxxxxx>
To: Linda Lawrie <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Mon, February 14, 2011 11:46:18 PM
Subject: RE: [EnergyPlus_Support] Problem with pumps

What you have shown are not complete demand loop, supply loops, etc. as described in the EPlus I/O manual and examples.

One boiler tank to supply all the demand is one plant loop. Look up the water heater tank object to see how the branches should be connected. The tank can be gas or electric heated, or puchased hot water. This is the supply side of the tank, which may have a pump.

The domestic main supply is connected to the tank use side loop which may have a pump, which is used as a control valve for domestic water intake.

DHW and radiant panels are all demand loop branches one one heater tank loop.

Bypass branch should be provided so that tank water can be circulated (pump) to maintain the temperature to the tank setpoint value, when there is no demand.

Draw a complete diagram with splitter and mixer and all the branches, and the domestic main water supply and the DWH water tempering valve, you will then have a better idea of the system. There is such a diagram in the I/O Ref. Manual.

Without looking at your IDF, I have no idea how you are simulating your system.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: lbarosow@xxxxxxxxx
Date: Mon, 14 Feb 2011 03:32:14 -0800
Subject: [EnergyPlus_Support] Problem with pumps

Hello Everyone,

I am trying to model a Radiator Heating system and I have a problem with the pumps. I've attached a scheme for more clearance. The water from the boiler is transported through a circulation pump (pump 1 on the scheme) and then distributed to four consumers, each on a separate branch. Each of these branches also has a circulation pump (pumps 2, 3, 4 and 5). When I try to model this exact situation in E+, the following error is being generated;

** An active component should not be present in the first branch in conjunction with branch pumps

** Current version does not support Loop pumps and branch pumps together

How should I proceed in this case? Should I remove the pumps 2, 3, 4 and 5 which are on the branches, or is it better to remove pump 1 and leave the rest? Or is there some other way to solve this and how would it reflect on the energy consumption?

Thank you!

Lyuben

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